The present invention relates to an image recording apparatus of an ink jet type that discharges ink from a nozzle and records an image on a recording medium.
Conventionally, as an image recording apparatus, there is a type that records an image by reciprocating a carriage, which contains an ink jet head for discharging ink from a nozzle and recording on a recording medium, in a direction orthogonal to a feeding direction of the recording medium. In the image recording apparatus of the ink jet type, a maintenance operation for sucking and removing the bubble staying inside the ink jet head, the ink hardened by dryness, and the like, from the nozzle side is carried out in order to maintain a discharging performance. For this reason, the image recording apparatus usually contains a maintenance unit, outside a record region where the ink jet head (carriage) records on the recording medium while moving therefore, and near the movement end of the ink jet head (carriage).
The maintenance unit contains a cap body, which is connected to and separated from the open surface of the nozzle. When the ink jet head is separated from the record region and moved to the position of the cap body, the cap body approaches the open surface of the nozzle and covers this. Then, the sucking operation and the like are carried out by a sucking pump connected to the cap body. The cap body is usually made of a rubber-shaped elastic body, and a protrusion towards the nozzle open surface side is formed. So as to surround the openings of the plurality of nozzles, the protrusions are adhered to the nozzle open surfaces.
On the other hand, the installed ink jet head is designed such that in association with the colorization in recent years, not only a black ink but also a plurality of color inks (for example, a yellow ink, a magenta ink and a cyan ink) can be installed, thereby discharging an ink color different for each nozzle row composed of a plurality of nozzles. However, as for the degree of the clogging of the nozzle and the like, for example, kinds (characteristics) of the inks of a dye group, a pigment group and the like are different for each nozzle row. Thus, when the maintenances of all of the nozzles were set under the same time and the same suck pressure, the useless sucking was performed on the nozzle whose clogging degree was little, which resulted in a problem that the sucked discarded ink amount was useless and the maintenance time was useless.
So, Japanese Patent Publication No. 2805361 discloses a configuration that contains: a plurality of caps for capping respective discharging ports (nozzles) of an ink jet head (recording head); and a plurality of sucking pumps for sucking from the corresponding discharging port when the cap caps the corresponding discharging port, where the maximum suck pressure when the plurality of sucking pumps are used to suck is made different, in accordance with a kind of a liquid or an aperture of the discharging port.
On the other hand, Japanese Patent Application Laid-Open No. 2002-36606 discloses a configuration that contains: a cap for capping respective discharging ports (nozzles) of an ink jet head (recording head) in which a plurality of nozzle rows including a plurality of discharging ports are installed; linkage valves for linking an inner space of the cap to atmosphere; and sucking pumps for sucking through the linkage valves from the discharging ports, where the cap is formed as the integral type so that the inner space is divided into a plurality of components, correspondingly to the plurality of nozzle rows, and the plurality of linkage valves are installed so as to be individually linked to the plurality of inner spaces, and an opening/closing unit of the linkage valve which, when the cap is brought into contact with the discharging port surface of the recording head, closes from or links to the atmosphere for each inner space.
All of them can adjust the ink suck amount for each nozzle row, on the basis of the thick or thin aperture of the discharging port and the characteristic of the ink, and consequently protect the ink from being uselessly sucked.